Attachment for saw blades



H. E. GRAHN ATTACHMENT FOR SAW BLADES March E4, 1950 Filed March '7, 1946 um. ma;

Patented Mar. 14, 1950 UNTED STATES TNT OFFICE 1 Claim.

This invention relates to saws of various kinds and classes, comprising a saw-blade and handle portion. More particularly, the invention deals with saws having means adjustably mounted on the saw-blade adjacent the handle portion to form oi the saw and in combination with the back edge of the saw-blade, means for marking a workpiece at different angles with respect to one edge of the workpiece, for example, in forming of the saw a square or miter. The novel features of the invention will be best understood from the following description when taken together with the accompanying drawing, in which certain embodiments of the invention are disclosed, and in which the separate parts are designated by suitable reference characters in each of the views, and in which:

Fig. l is a plan view of a saw showing my attachment in a normal position with respect to the handle, with part of the construction broken away.

Fig. 2 is an enlarged section on the line 2 2 of Fig. 1.

Fig. 3 is a view similar to Fig. 2 showing the attachment in an offset or flexed position preparatory to shifting the same to diierent positions on the saw-blade; and

Fig. 4 is an enlarged section on the line 4 4 of Fig. 2, showing only the saw-blade and the attachment thereon.

In Fig. l of the drawing, I have shown at I a blade of a conventional type of saw, the blade having a straight back edge il and an angular saw tooth edge l2. At i3 is shown a handle portion secured to the wide end portion of the saw by screws or other fastening devices i4.

The handle member adjacent the straight v back edge l! is recessed, as seen at i5, to re ceive enlarged pivot portions i5 of two back members or bars il and i8, note Figs. 2 and 3. Passed through the blade l0 and fixedly secured in the enlarged portions I6 of the bars ll and i8 is a pivot pin i9 securely held in the bars by key-pins, at at 20-2l. The bars i? and I8 have straight faces or longitudinal edges 22 and 23, note Fig. 4, which operate in conjunction with the straight ba .t edge H of the saw in forming different angular positions with respect to said edge. For example. at right angles to the edge ll, as indicated at 22' in Fig. l, and at forty-five degrees to the edge il, as indicated at 22", it being understood that the edge 23 of the bar or backing I8 assumes the same positions.

The bar il around the pivot pin i8 has a recess 2i in which is placed a heavy spring 25, so as to rrnly maintain the pivot ends oi the bar I8 upon the saw-blade l0. The recess 2d is formed on the inner surface 26 ol the bar il', and another and deeper recess 2l opens through this surface and in which is arranged a lighter coil spring 2B which is adapted to bear upon the surface of the blade l0.

In the construction shown, the blade I0 has three apertures 29, 30 and 3l, all equally spaced radially with respect to the pivot i9, but positioned on the blade to xedly support the backing attachment comprising the bars il and I8, rst adjacent the handle I3, as shown in full lines in Fig. l, and then in the two positions where the surface 22 is at right angles and fortyfive degrees to the edge il, as indicated at 22'-22. This positioning of the attachment vor the bars l'i and I8 is accomplished by a pin 32 having a pressed or drive fit in the bar E8 and protruding inwardly beyond the inner surface 33 of said bar to enter the apertures 29, 30 and 3 i.

The inner protruding end of the pin has slightly rounded corners as at 34, note Fig. 4, to freely guide the pin into the respective apertures 29, 30 and 3l, whereas the pin is tted snugly in the apertures and particularly the apertures 30 and 3l to maintain a rigid backing in providing a T-square and the miter, as shown in the two dotted line positions of Fig. 1 of the drawing.

The surfaces and 33 are relieved at the free ends of the bars, as seen at 26 and 33' in order to prevent these surfaces from contacting the blade l0 as the bars assume the different positions shown in Figs. 2 and 3. The ends of the bars are also bevelled, as seen at 35, note Fig. 1, to conform to the general contour of the handle i3 and eliminate any protruding corner which might be objectionable.

The upper surface of the handle i3, as seen in Fig. l of the drawing or the surface adjacent the bar 17, has a thumb-notch or recess 3S to facilitate engagement of the nger with the rear or back surface 3l of the bar ll in the operation of moving the attachment from the normal full line position shown in Fig. l, which may be regarded as a collapsed position, to either of the dotted line positions shown in said figure. In this operation, the bar l1 is rst depressed to disengage the pin 32 from the aperture 29, after which the bar is swung outwardly. Thereafter, the downward pressure may be removed from the bar Il and the pin 32 will then ride along the surface of the blade until the iirst aperture is reached. When the pin registers with this aperture, it will automatically snap into the aperture, returning the bar i'i to the position shown in Fig. 2, in which position the bars il and I8 are rigidly locked and become a unit part of the blade.

Considering Fig. 2, it will be apparent that in the normal locked position of the attachment the surface 33 bears snugly upon the face of the saw-blade lil, whereas the surface 26 extends outwardly in an angular or inclined position, in the direction of the free end of said bar. However, in this position, it will appear that the entire attachment is disposed within the boundaries of the upper and lower surfaces of the handle i3 and this is true in any position of the attachment and is particularly desirable when the attachment is in the collapsed or normal position so as to not provide any obstructions on the saw when the saw is in use.

Now noting Fig. 3, it will appear that when pressure is applied on the bar Vi, the surface 33 is moved away from the blade adjacent the keypin 32 and the surface 26 kcontacts the blade i6 adjacent the apertures 29, 3U and 3i. This position clears the inner end of the pin 32 to allow the attachment to be freely swung on the blade. 1n this connection it will be noted that there has been little or no movement of the pivot end portions of the bars il' and I8, the spring 25 serves to hold these bars in snug and taut arrangement. In fact, in actual practice, the holding at the pivot end is such as to slightly1 spring or eX the saw-blade and it is this flexure in combination with the springs 25 and 28 that results in the snapping of the key-pin 32 into the respective apertures.

It will be apparent that by employing additional apertures, such as the apertures 29, 30 and Si other angular positions may be obtained in scribing different angles upon a workpiece preparatory to cutting the same. It will appear from a consideration of Fig. 1, that a slight clearance is provided between the square and mortise attachment and the handle when the attachment is in the normal or full line position. This is to insure positive movement of the key or lock pin into the aperture 29.

By providing the attachment, the saw may be converted into a T-square, wherein the attachment provides the equivalent of the backing of the square for placement against the edge of a board or other sheet to be marked. The straight edge li provides a long marking edge, considerably longer than the average T-square used by the carpenter or workman. By disposing the rods il and is on each surface of the saw-blade ill, the edge i i may be extended to the right or to the left for marking purposes. In this way, fortynve degree lines with respect to the edge may be scribed or marked in either one of two directions. The foregoing will also be true in connection with other angular positions which can be employed by increasing the number of holes 29-3l employed in the blade i9. The structure shown is the simple basic requirements for conventional uses, but some workmen may desire to mark other angles.

By incorporating the attachment comprising the two bars I1 and I8 on the saw, the need for a workman to carry the extra tool, namely a square, in his tool kit is obviated. Furthermore, material saving of time will be eifected by reason of the fact that the square or mortise marking tool is directly available on the saw and markings can be quickly and easily made without having to take the time to rind or pick-up a square or miter and thereafter to nd or pick-up the saw to be used.

It will also be understood that each saw of a complete kit may have the attachment applied thereto, particularly in that the attachment is of simple and economical construction and will not add materially to the cost of the saw. Furthermore, the addition of the attachment to the saw adds a little weight to the handle end of the saw which provides a better balance in the use thereof and by reason of its weight, adds to the driving power of the saw.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent is:

A square and miter attachment for saw blades having straight back edges, said attachment comprising a pair of hars, means comprising a pin coupled with said bars for pivotally and yieldably mounting one end of the bars with a saw blade, one bar, at a predetermined distance from said pivot coupling having a key element secured thereto and projecting from the inner surface thereof, the saw blade having a recess adapted to be snugly engaged by said key element in retaining the bar in predetermined position on said blade, the other bar having, on the inner surface thereof, a recess spaced from, but adjacent, said key element, a spring in said recess and adapted to seat on the saw blade to tensionally hold the key element in operative position, and the inner adjacent surfaces of the bars at the free end portions thereof being relieved beyond said key element to provide pivotal and yielding movement of the bars against the action of said spring in coupling and uncoupling the key element with the blade.

HARRY E. GRAHN.

REFERENCES CETED The following references are of record in the file of this patent:

UNTED STATES PATENTS Number Name Date 1,187,650 Rasmuson June 20, 1916 1,277,433 Larson Sept. 3, 1918 1,338,188 Mendel Apr. 27, 1920 1,644,619 Telper Oct. 4, 1927 1,954,049 Jeffrey Apr. 10, 1934 2,271,806 Schilf Feb. 3, 1942 FGREGN PATENTS Number Country Date 544,899 France July 6, 1922 

